Research suggests the stem cells in our teeth can be energized to fill in chips, cracks, and cavities

The stem cells in our teeth can be energized to fill in chips,
cracks, and cavities, researchers say, and the findings could one
day possibly make dental cement obsolete.

The work has been conducted just in mice so far,
but the research, published Monday
in the journal Scientific Reports, highlights a way to motivate
stem cells to repair tooth defects at a scale they normally
can’t, with a drug that already has some safety testing behind
it.

It also demonstrates the potential of a type of stem cell therapy
in which the cells are stimulated in place, rather than taken
out, manipulated, and put back in.

“We’re mobilizing stem cells in the body and it works,” said Paul
Sharpe, a researcher at King’s College London and an author of
the new paper. “If it works for teeth, chances are it could work
for other organs.”

Experts not involved with the work noted that while it is in
early stages, the simplicity of the approach should ease its path
into the next phases of research that show whether it might
produce the same results in people.

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“These important steps close down the translational gap and bring
this discovery a step closer to future clinical applications,”
Dr. Vanessa Chrepa, a researcher at the University of Washington,
wrote in an email. “This work will hopefully set the stage for
clinical studies in the near future.”

When teeth lose some of their dentin — the bony tissue beneath
the enamel that makes up the bulk of the tooth — the stem cells
tucked deep inside mount a recovery effort and manufacture new
dentin (which is also spelled dentine). The problem, Sharpe said,
is that the natural repair mechanism can only regrow small
amounts of dentin and can’t make up all that is lost when a tooth
suffers a serious injury, contracts a major infection, or takes
on the sharp end of a dentist’s drill.

Because of the limits of the teeth’s ability to repair
themselves, dentists have to fill or seal teeth to prevent
further infection and degradation. But dental cement also
prevents the tooth from ever returning to its natural, pearly
white self.

Sharpe and his team have been trying to understand how the
natural repair mechanism works in hopes of converting that
understanding into a way to super-power it. As part of their
research, they discovered that a group of molecules called
glycogen synthase kinase inhibitors (or GSK-3 inhibitors) boosts
the stem cells’ ability to stimulate production of dentin beyond
what normally occurs.

Having
bad teeth could disqualify one from being a motor vehicle
inspector in Andhra PradeshPeter
Macdiarmid/Getty Images

For the new study, the researchers drilled tiny holes into mice’s
molars to expose the tooth’s pulp, where the stem cells live.
They then inserted collagen sponges that had been soaked in one
of three types of GSK-3 inhibitors and covered the tooth.

After six weeks, the researchers removed the teeth and found that
the sponges had dissolved and the lost dentin had mostly been
regenerated.

“They’ve harnessed the signaling pathway that promotes natural
repair,” said Megan Pugach, a researcher at the Forsyth Institute
in Cambridge, Mass., and at the Harvard School of Dental
Medicine, who was not involved with the research.

Sharpe and his team are now conducting similar studies in rats to
make sure the approach can generate enough dentin to fill in
larger holes in larger teeth before trying to study the method in
people. But two aspects of the approach could help ease its path
into clinical trials.

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Nudelman

First, the researchers used collagen sponges that are already
commercially available and are shown to be safe. Secondly, one of
the GSK-3 inhibitors they used, called Tideglusib, has been
tested in people as a possible therapy for Alzheimer’s disease,
meaning it is already shown to be safe in higher doses than what
the researchers would incorporate into the sponge.

“In terms of getting that into the clinic, we can make a huge
leap,” Sharpe said.

Sharpe and other researchers around the world have been studying
if and how teeth stem cells could be used to regenerate a whole
tooth, possibly one day replacing dentures or implants. But teeth
are complex organs, with both hard and soft tissue, so that goal
remains further away.

Because this approach is just focused on dentin, “it’s a bit more
low-hanging fruit,” Sharpe said. But this study also adds to the
possibility of stem cell therapies, which
are much hyped, but for the most
part have yet to be developed
into validated treatments

“This is a very clear, simple demonstration that with basic
knowledge of what happens normally in the body, you can design
something that can enhance that,” he said.